Method of making embossing rolls by engraving mills



Oct. 26, 1965 v. F. Dl LEO ETAL 3,

METHOD OF MAKING EMBOSSING ROLLS BY ENGRAVING' MILLS Filed June 29, 1962 VVVVVVVV V Z a 5 55) 0 F Z mmzfi w fin 5/1 2 i any M M 2 a INVENTORS V/IVCE/YT I'D/[0 farm/70 F0001! Bwg uu $6M ATTORNEYS;

.the mill. design in recess onto a large soft steel cylinder which cumferential dimensions. held under a tremendous pressure against the relatively United States Patent METHOD OF MAKING EMBOSSING ROLLS BY ENGRAVING MILLS Vincent F. Di Leo, Bound Brook, and Edward P. Rodcn, Leonardo, N31, assignors to Modern Engraving and Machine Company, Hillside, N ..I., a corporation of New Jersey Filed June 29, 1962, Ser. No. 206,211 6 Claims. (Cl. 15614) This invention generally relates to the art of embossing, and particularly to the manufacture of embossing cylinders or rolls by an improved engraving mill. In greater particularity, the invention relates to manufacturing a female embossing roll which is of such small dimension, especially axially, that there needs to be no stepping of a mill axially of the female roll during the engraving of the latter by the mill. This invention gives the advantage that the female roll may be fully hardened, or just case hardened if so desired, before the design is engraved into the roll by the mill.

In the art of manufacturing embossing rolls, it is common to use what is referred to as the die and mill method. This generally refers to making a relatively soft small steel cylinder into a die by placing a design around its periphery in intaglio, generally using hand tooling to obtain the depth and rounded edges desired. Then a mill is made from the die, by hardening the die and .rolling it in contact under great pressure against the surface of another soft steel cylinder of the same size as the die cylinder. This puts the design in relief on The mill is then hardened and used to put the becomes the final female embossing role. This roll is generally large relative to the mill in both axial and cir- Heretofore the hard mill was soft surface of the potential female embossing roll while the roll was rotated. Traction between the mill and roll was effected largely only because the roll was soft relative to the hardened mill, so it is apparent the roll could not be pro-hardened before being engraved by the mill, as

it can be in accordance with the present invention. After one circumferential strip of mill length had been engaged on the roll by the mill, it was then necessary to step the mill axially its length to effect engraving of the roll by the mill around a second circumferential strip.

The present invention is particularly useful for the manufacture of embossing rolls that do not repeat the design in an axial direction any more times than does the mill itself, which is usually only once. In other words, in accordance with an object of this invention provision is made for the manufacture of embossing rolls by use of a mill without stepping the mill longitudinally of the roll. Additionally, this invention provides the opportunity of fully hardening the potential female embossing roll before engraving same with a mill, but without losing traction between the mill and roll during the engraving process. These objects and advantages are accomplished by this invention, in one embodiment by effecting apertures around one if not both ends of the periphery of the die so that the mill made therefrom has corresponding pins protruding from its surface. Then, soft metal rings are disposed adjacent the ends of the potential female embossing roll, these rings being slightly larger in diameter than the embossing roll, so that when the mill is rotated under pressure towards the embossing roll, the pins protruding from its surface will bite into and maintain traction with the embossing roll in a gearinglike manner to effect accurate registry between the mill and embossing roll.

3,214,310 Patented Oct. 26, 1965 These and other objects and advantages of this invention will become apparent to those of ordinary skill in the art upon reading the appended claims and the following detailed description, in conjunction with the drawings, in which,

FIGURE 1 represents a die with gearing apertures effected in rings around its ends,

FIGURE 2 represents a mill made from the die of FIGURE 1, in engagement with an embossing roll having soft rings secured to its ends for gearing to the pins of the mill, and

FIGURE 3 represents a resultant female roll and a male embossing roll made therefrom.

The die 10 of Figure 1 may be made from a soft steel cylinder that has journals 12 disposed at its opposite ends. In the central area 14 around the surface of the die a design of desired nature is engraved in intaglio by any one or more of the convenient manners of effecting such. For example, the design may be first photoengraved to a shallow depth in the die 10 by using a positive photographic film of a master art work, and then deepened and edges rounded by hand tooling. On the other hand, a hand tooler may put the design on the die without any photoengraving or other like process first registering any part of the design.

It makes no difference how the design is engraved on the die 10 as far as this invention is concerned, but it is a part of one embodiment of this invention that a circumferential or peripheral strip 16, of desired axial length, at least one end, preferably both ends, be free of the design. Strips 16 are caused, either before the design is engraved into the mill or thereafter, to contain a plurality of indentations such as apertures 18, which are preferably punched into the die though they may be photoengraved or otherwise produced therein. There need not be any regularity about the location of the apertures, but generally it is preferred to have two staggered rings of apertures at each end, with the apertures being spaced circumferentially appropriately to effect a desired number of gearing pins 20 (FIGURE 2) in the mill 22 that is made from the die. It is preferable that pins 20 protrude with a conical shape, so indentations 18 are also conically shaped as shown in FIGURE 1.

The making of mill 22 from die 10 is accomplished by first hardening the die, for example by furnace or flame hardening. Then, the hardened die is rotated in contact with the potential mill which at that time is a relatively soft steel cylinder of the same axial and circumferential dimensions as die It). Sheer pressure of the die onto the mill while the mill is being positively rotated causes the mill to be engraved with the design of the die effected in relief on the mill. For purposes of rotating the mill, it has journals 24 at its opposite ends. Besides the resultant design being in relief on mill 22, the resultant pins 20 protrude from each of its ends at positions matingly corresponding to apertures 18 of the die. These pins of course are located around the peripheral ends of the mill, i.e., in circumferential strips 26.

After being made from the die, the mill is case hardened and then is ready to be rolled against a potential embossing roll 28 as shown in FIGURE 2. It will be noted roll 28 itself (i.e., to the exclusion of rings 34)) has an axial length just slightly greater than the axial length of the design area 14 on the die or mill, though the axial length of the embossing roll 28 may be exactly the same as the length of area 14, if desired. At each of its ends, roll 28 has secured to it soft metal rings 30, soft here meaning that they are not as hard as the mill and especially its pins 20. In addition, rings 30 are softer than roll 28. That is, roll 28 is initially a steel cylinder that has been hardened and finished ground, i.e. such is done before it is engraved by the mill. As previously indicated it is preferred, and in many cases aboslutely essential, according to the material and design to be embossed by the engraved roll, to pre-hardened the cylinder 28 to full depth. It is possible to do so by this invention, since, as will become more apparent, it is possible to engrave cylinder 28 by the mill even if it is pre-hardened. Prehardening gives not only the opportunity of full depth hardening, but also the advantage of not being required to take the chance of distorting or otherwise damaging the design produced in the embossing roll by an afterhardening process. The best way known to harden a steel embossing roll after it is engraved, is to case harden it with flame hardening equipment, but this has the disadvantage of hardening only the case of the roll, and may even at times distort or damage the design engraved on the roll.

As indicated in FIGURE 2, cylinder 28 has a shaft 32 that integrally extends from the cylinder in opposite directions' The metal rings 30 may be secured to this cylinder in any desired manner, as by shrinking same onto shaft 32, or pinning them to the cylinder ends, or, as illustrated, using keys 34 in keyways provided in the shaft and rings. In any event, the rings are so secured to the cylinder that there is no possible slippage between the cylinder and rings.

As will be noted from FIGURE 2, the diameter of rings 30 is slightly larger than the diameter of cylinder 28. The purpose for this will become more apparent as this description proceeds. The diameter of cylinder 28 is such that its circumference is any integral number of times the circumference of mill 22, for example the embossing roll circumference may be twice as large as the circumference of mill 22, as indicated in FIGURE 2 by the legends and division of the roll circumference into two parts with a dash line, no limitation being intended as to this ratio of circumferences since the embossing roll may be equal to or many times larger than the mill.

As indicated above, the soft rings 30 are slightly larger in diameter than the diameter of cylinder 28, for example 0.0l inch larger. Therefore, when mill 22 is pressed toward the cylinder with rings 30 intact while the latter are being rotated via shaft 32, the protruding mill pins 20 on the ends of the mill will contact the soft metal rings before the relief design on the mill contacts cylinder 28. Since the rings 30 are softer than pin protrusions 20, the pins will effectively dig or bite conforming indentations or apertures 36 into the rings and thereby set up a geared relationship between the mill and embossing roll so as to effect positive traction therebetween and prevent slippage so that continued registry can be maintained without question between the relief design on the mill and the mating recess designs being engraved onto the cylinder 28.

In engraving cylinder 28 to make it into a female embossing roll, it and metal rings 30 are first coated with an acid resist material, such as an asphaltum base composition, before the mill is pressed against the cylinder and rings. Afterwards shaft 32 is caused to rotate with the mill bearing down under pressure onto the cylinder and rings, to cause parts of the resist material to be removed, first from the metal rings 30 because of mill pins 20, then from certain regions of cylinder 28 because of the protrusion of the mill design. In this manner, the metal of the rings and cylinder become exposed only at the desired places. Cylinder 28 and rings 30 are then etched in an acid bath 31 to eat away the metal in the regions on the rings and cylinders where the pins 20 and relief design on the mill have removed the resist material. Several such coating-etching cycles are usually required during the first one or few of which the protruding design on the mill may not remove the resist material deep enough to expose any metal of cylinder 28. But at the same time pins 20, because of the larger diameters of metal rings 30, expose circular metal areas on the rings with the etching of those exposed metal areas thereon effecting the beginnings of apertures 36 that thereafter continue to mate respectively with pins 20 to effect the positive traction and permanent registration desired between the mill and cylinder 28.

After cylinder 28 is fully engraved by use of mill 22, keys 34 and rings 30 may be removed from the cylinder shaft, thereby leaving a fully hardened embossed female roll 28, shown in FIGURE 3. This roll may then be utilized to make a mating male roll by the resist-etch process fully described in the Sunderhauf et al. Patent 2,662,002, using herringbone gears 38 and 40, the former of which is secured to shaft 32 of the female roll, and the latter of which is secured to the shaft of the male embossing cylinder or roll 42. Preferably, male roll 42 is also pre-hardened to full depth before it is provided with its mating design.

From the foregoing description it is apparent that thisinvention has provided a process for making an embossing roll with positive traction effected between the mill and embossing roll during the engraving of the latter by the former. Such traction is effected by what has been termed snag gearing, referring to the protruding pins 20 or snags provided on the ends of the mill for snagging themselves into soft metal rings secured to the embossing roll. As previously indicated, this gives the opportunity of pre-hardening the embossing roll to full depth, which is not possible without some sort of positive traction or gearing between the mill and embossing cylinder being engraved thereby. Because of the positive traction provided by the snag gearing effect, less pressure is required on the mill to engrave the roll.

Though the Sunderhauf et al. Patent 2,662,002 referred to above indicates that two rolls may be geared together by herringbone gears to effect positive traction and permanent registry between the rolls, and though it might be possible to provide the journals of mill 22 and cylinder 28 wtih such gears and cause positive traction therebetween, the present invention is preferred from the standpoint of being able to make any number of female embossing rolls of various diameters without the necessity of first having to make a new set of herringbone or like type gears for the journals of the mill and rolls. As is well known, the making of herringbone gears, or other gears that operate with a similar lack of backlash, is an expensive and time consuming operation. However, such time and expense is obviated by this invention, since it is only necessary to secure to one end, preferably both ends, of the potential embossing roll a soft metal ring into which the pins 20 on the mill can bite and effect positive registration.

It is therefore apparent that this invention has provided all the objects and advantages herein indicated. It will be appreciated by those of ordinary skill in the art after reading this disclosure that no limitation is necessarily intended by the details disclosed since this invention is defined by the spirit and scope of the appended claims.

What is claimed is:

1. In the process of manufacturing an embossing roll by engraving same with a cylindrical mill, the improvement comprising the steps of:

producing integrally with said mill on the cylindrical face of the mill itself around at least one peripheral end thereof a plurality of circumferentially spaced substantially pointed radial protrusions, and engraving indentations, by use of said mill and resist coating and etching, in a ring about a potential embossing roll in conformance with said rotrusions for providing positive gearing-type traction and ac curate registration between said roll and mill.

2. A process as in claim 1 including the steps of:

forming a plurality of indentations around the surface of at least one end of a die, and

producing said mill as aforesaid by engraving same with said die to cause said protrusions to respectively correspond in all respects substantially to the said indentations on said die.

said potential embossing roll before securing said metal ring thereto.

6. A process as in claim 3 including the step of engraving said potential embossing roll by said mill after 3. A process as in claim 1 including the step of de- 5 engraving said indentations in said ring.

tachably securing to one end of said potential embossing roll a gearless metal ring which is soft relative to said protrusions and which is engraved thereby as aforesaid.

4. A process as in claim 3 including producing the aforesaid radial protrusions around both ends of the mill periphery, securing a second similar metal ring to the other end of the potential embossing roll, and engraving the second ring with the mill protrusions around the other mill end in conformance therewith simultaneously with the engraving of the first mentioned ring to provide positive traction between the roll and mill at both ends thereof. 5. A process as in claim 3 including fully hardening References Cited by the Examiner UNITED STATES PATENTS ALEXANDER WYMAN, Primary Examiner. JACOB STEINBERG, EARL M. BERGERT, Examiners. 

1. IN THE PROCESS OF MANUFACTURING AN EMBOSSING ROLL BY ENGRAVING SAME WITH A CYLINDRICAL MILL, THE IMPROVEMENT COMPRISING THE STEPS OF: PRODUCING INTEGRALLY WITH SAID MILL ON THE CYLINDRICAL FACE OF THE MILL ITSELF AROUND AT LEAST ONE PERIPHERAL END THEREOF A PLURALITY OF CIRCUMFERENTIALLY SPACED SUBSTANTIALLY POINTED RADIAL PROTRUSIONS, AND ENGRAVING INDENTATIONS, BY USE OF SAID MILL AND RESIST COATING AND ETCHING, IN A RING ABOUT A POTENTIAL EMBOSSING ROLL IN CONFORMANCE WITH SAID PROTRUSIONS FOR PROVIDING POSITIVE GEARING-TYPE TRACTION AND ACCURATE REGISTRATION BETWEEN SAID ROLL AND MILL. 